The Palazzo Castellani, site of the Istituto e Museo di Storia della Scienza since 1930, nowadays Museo Galileo, is a building of very ancient origin, dating from the late 11th century. Known at the time of Dante as Castello d'Altafronte, from the name of the family who owned it until 1180, when it became the property of the Uberti, the Castello was inserted in the city's very oldest ring of walls. After having passed from the Uberti to the Castellani family in the 14th century, it was the site, from 1574 to 1841, of the Giudici di Ruota (magistrates or judges of the high court of the Grand Duchy); even today the coats-of-arms of two of the magistrates remain on the walls of the entryway and remind us of this function. No documentation exists on the functions of the building in the 17th and 18th centuries. During the first half of the 19th century, the Palazzo underwent large-scale restoration. After the Unification of Italy, the collections of manuscripts owned by the Biblioteca Nazionale (National Library) were transferred to the Palazzo, where they remained until the 1920s. The Palazzo has also housed the Accademia della Crusca and the Deputazione di Storia Patria per la Toscana. Today, the Museo Galileo occupies the whole building. The spaces have been restored and adapted to the new uses. The work of restoring the basement level, carried out over the two-year period 2002-2003, has brought to light the four massive stone foundation arches of the ancient Castello d'Altafronte. Situated in the heart of Florence, on the Arno, near the Galleria degli Uffizi, the Palazzo is a Medieval building with a facade of bare stone. It rises for six floors and is distinguished by rounded windows and rusticated stone arches. The Palazzo Castellani is the property of the Italian State, which in turn leases it to the Museo Galileo at a token fee.